2.3.5 Idle Completions Mode

Semantic Idle Completions mode is a minor mode for performing
code completions during idle time. The completions are
displayed inline, with keybindings that allow you to cycle through
different alternatives.

This command toggles Semantic Idle Completions mode in every
Semantic-enabled buffer. You can also toggle it via the ‘Show
Tag Completions’ menu item in the ‘Development’ menu.

If the tag at point has at least one completion, Semantic Idle
Completions mode displays that completion inline—i.e., as part of
the buffer text (you can change the display method by customizing
semantic-complete-inline-analyzer-idle-displayor-class, as
described below). The completed part is highlighted, to indicate that
it is not yet properly inserted into the buffer. The echo area shows
the completion, and whether there are other possible completions, like
this:

besselj [1 of 6 matches]

While the completion is being displayed, the following keybindings
take effect:

RET

C-m

Accept the current completion (semantic-complete-inline-done),
placing it in the buffer and moving point to the end of the completed
tag.

M-n

Select the next possible completion
(semantic-complete-inline-down). The new completion is shown
inline, replacing the old completion.

Accept as much of the completion as possible. If no additional
completion can be accepted without ambiguity, select the next possible
completion (semantic-complete-inline-TAB).

C-g

Quit without completing (semantic-complete-inline-quit).

You can also exit inline completion by issuing any other Emacs
command. The completion text then disappears from the buffer.

Command: semantic-complete-analyze-inline-idle

This is the command for performing inline code completion. It is
called by Semantic Idle Completions mode during idle time, but you can
also call it yourself. It returns immediately, leaving the buffer in
a state for inline completion.

Option: semantic-complete-inline-analyzer-idle-displayor-class

The value of this variable determines how
semantic-complete-analyze-inline-idle shows its completions.
Possible values include:

semantic-displayor-ghost

Display completions “inline” with the buffer text, as described
above. This is the default value.